1. Field of the Invention
The present invention generally relates to an antenna and bandwidth increasing and resonant frequently tuning method thereof.
2. Description of the Prior Art
Dielectric resonators made of low-loss and high-permittivity material have been used to implement antenna. They have higher radiation efficiency than printed antennas at higher frequency due to the absence of ohmic loss and surface wave, in addition to compact size, light weight, and low cost.
Many efforts have been devoted to developing multi-band or wideband DRAs. For example, make the feeding aperture radiate like a slot antenna to incur another band, induce parasitic effects with attached metal strips.
In [C. S. D. Young and S. A. Long, “Investigation of dual mode wideband rectangular and cylindrical dielectric resonator antennas,” IEEE APS Int. Symp., vol. 4, pp. 210-213, July 2005.], specific higher-order modes with the electric field distribution on the top surface of the DR similar to that of the fundamental mode are intentionally excited. In [A. A. Kishk, “Wide-band truncated tetrahedron dielectric resonator antenna excited by a coaxial probe,” IEEE Trans. Antennas Propag., vol. 51, no. 10, pp. 2913-2917, October 2003.] and [A. A. Kishk, Y. Yin, and A. W. Glisson, “Conical dielectric resonator antennas for wide-band applications,” IEEE Trans. Antennas Propag., vol. 50, no. 5, pp. 469-474, April 2002.], higher-order modes of truncated conical or tetrahedral DR are excited to obtain wide impedance bandwidth.
DRs of different sizes have been placed vertically to form a stacked DRA, or at close proximity to form a multi-element DRA to attain wideband or dual-band features.